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Knocking sound when I turn on the air conditioner

phillippdunn

New Member
Joined
Jul 17, 2015
Messages
7
Mine is a 2003 105 series diesel Landcruiser standard model purchased January 2018.

When I turn on the air conditioner there is a distinctive knocking sound from the engine. I turn of the ac and it goes. I have loosened the the ac pulley and but the belt slips when i engage the ac.

Can i replace a bearing in the drive shaft without dismantling the ac unit.
Have taken it to several ac people and they cannot understand the noise and have offered no solution ?

Any recommendations for a supplier of a new ac compresser

Any ideas or similar problems

phillipp dunn
 
Hi Phillipp, try and find exactly where the knocking is coming from and don’t replace or condemn anything until you do or you could be wasting your time and money.

Once you’ve done that remove the belt and check if the compressor pulley is firmly seated. Sometimes the circling comes off but I would expect yours to be ok as it’s only knocking when the compressor is working.

Does your AC work correctly otherwise? Is it just the one knock or is it continuous?
Finally if you do need to replace the compressor go for an exact replacement Denso or Sanden (Denso) unit. The Chinese copies are not good. There’s various threads on here with sources if you do a search. Also search for Frankenstein on here where a rebuild was done making one good compressor from two bad.
 
The ac works well. As I said the knocking occurs when I turn on the ac. If I tension the drive belt so that it doesn't slip with ac on the knock is continuous ac on and off.
 
The ac works well. As I said the knocking occurs when I turn on the ac. If I tension the drive belt so that it doesn't slip with ac on the knock is continuous ac on and off.
In that case inspect the tensioner as well as the compressor pulley. The pulleys can work off the end of the nose on the compressor if you’re unlucky. It’s a 10mm socket to gat the clutch plate off then remove the belt and see if there’s any slack or notchiness in the pulley bearing. This turns at all times regardless of whether or not the AC is working.
 
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